The general objective of this project is to examine the temporal response characteristics of the middle- and long-wavelength color vision mechanisms in normal and anomalous trichromatic humans. Human middle-and long-wavelength color vision mechanisms, having inputs from more than one cone type, show different patterns of response to temporally-modulated chromatic stimuli. The effect of variations of temporal frequency, modulation amplitude, phase, duty cycle, and waveform of two counterphased monochromatic lights upon color perception should reveal several characteristics of the color vision mechanisms. Among these characteristics are phase relationships, response latencies and integration times. By using the Rayleigh match as the major psychophysical technique for exploring the response characteristics of the chromatic mechanisms, this study will allow direct comparison of the information processing by normal and anomalous color vision systems, irrespective of photopigment abnormalities.